This invention relates to a process for treating waste water having a relatively high chemical oxygen demand caused by organic material which is predominantly soluble in water. It is well known in the art to use a biochemical treatment step followed by carbon absorption in the treating of municipal sewage. Use of biochemical treatment is also known for waste water from chemical plants as evidenced by Hudson, Jr. et al, U.S. Pat. No. 3,646,239.
Waste water from chemical plants generally differs substantially from municipal sewage in that it contains a higher concentration of organic matter and in addition, this organic matter is predominantly soluble whereas in municipal sewage the organic matter is predominantly solids. The high concentration of organic matter having a chemical oxygen demand in waste water from chemical processes makes the treatment of this water extremely difficult. For instance, in a municipal sewer plant, chemical oxygen demand may be no more than 300 to 400 milligrams per liter and a 90 percent reduction leaves the effluent within generally accepted standards whereas with waste water from a chemical plant which may have a chemical oxygen demand of 2500 or more, a 90 percent reduction leaves the effluent still unsuitable for disposal.